The present invention relates to an IP (Internet Protocol) communications network system capable of guaranteeing, based on an RSVP (Resource Reservation Protocol), a QoS (Quality of Service offered by the network) of data communications containing backbone data about an order entry operation, etc. via an IP packet switching network such as the Internet or the Intranet (an intraoffice IP network).
With an advancement of the networking technology as typified by enhancing functions of a local area network (LAN) and expanding the Intranet and an advancement of a personal computer (PC) technology as typified by attaining further multi-functions of the PC and a further speed-up of a Central Processor Unit (CPU) over the recent years, a variety of information can be communicated at a high speed between the PCs on a plurality of LANs (subnetworks) at a stage of its utilization.
Further, a spread of electronic mails (e-mails) and an expansion of WWW (World Wide Web) are seen, and multimedia data such as motion picture information, voice information, etc. are increasingly utilized and spread out. Moreover, an occupying rate of Internet Protocol among protocols used for the data communications rises, and this tendency, it can be presumed, will show a farther progress from now on into the future.
The infrastructures of the networks have been established, wherein the general data communications (IP data communications) are realized without any inconvenience at the present. A demand under this circumstance is that a QoS for every specified IP data communication be guaranteed. For example, with respect to consecutive pieces of multimedia stream data such as the motion picture information and the voice information, network resources such as a transmission bandwidth are reserved based on the RSVP in order to make it feasible to smoothly reproduce the voice information and the motion picture information irrespective of a state of a traffic load on a transmission path between transmitting/receiving entities (the PC and workstation (WS)) and a delay and a jitter are restrained within a fixed range, whereby the QoS guarantee requested can be attained.
At the present, there are commercialized networking devices implementing the RSVP, a PC operating system (OS) adapted itself to the RSVP and multimedia applications corresponding to the RSVP.
Further, there exist data communications of which the QoS guarantee for attaining a low delay, etc. is requested other than the data communications aiming at the multimedia data. For instance, the communications for the backbone data on an order entry operation and a bank accounting operation directly linked to profits of enterprises, are of high importance to the enterprises as well as being the data communications requested to provide a high quality transmission with the delay, etc. restrained. What is required of such data communications is an architecture by which the data can be always transmitted with a low delay regardless of a traffic load state of the network between client terminals and a server (a host computer).
Moreover, those backbone operations are on the shift to the IP coming under the same category as other information communications protocols for the e-mails and the WWW from a conventional SNA (Systems Network Architecture) and FNA (Fujitsu Network Architecture) defined as network architectures (network OS) of the manufactures (vendors) in terms of reducing the network management costs. There is a strong demand for merging information system communications for the WWW and the e-mails with the IP-based backbone communications on one single circuit in terms of decreasing the network management costs. If merged, however, there might arise a problem in which a preferable response of the backbone data communications is hindered because of being oppressed by traffics in other information system communications especially at the WAN exhibiting a comparatively low transmission speed, i.e., at the IP packet switching network.
Accordingly, the present situation is that a leased line is extended separately from the information system communications in order to secure the transmission quality for attaining the low delay in the backbone data communications.
As described above, there is the strong demand for merging the communications protocols with the IP and for reducing the network management costs, however, some sort of architecture for guaranteeing the QoS is needed for the communications of the backbone data exhibiting a high importance. For example, if scheming to apply the RSVP to the QoS guarantee for the backbone communications and the client-to-server communications in which a multiplicity of terminals transmit data packets at random, the RSVP is required to guarantee the QoS on a session basis, in other words, on a TCP/IP (Transmission Control Protocol/Internet Protocol) connection basis, or a UDP/IP (User Datagram Protocol/Internet Protocol) transmission-side and destination port pair basis.
Therefore, if the individual client terminals implement the RSVP for guaranteeing the QoS of each item of data, a networking device such as a router supporting the RSVP must execute the RSVP processes corresponding to the number of terminals (over several hundreds—several thousands of terminals). As a result, a processing load increases, whereas a response is impaired, and the RSVP can not be substantially, if as it is, applied to the QoS guarantee for such communications.
Further, a QoS guarantee target traffic of the RSVP is mainly the multimedia data such as motion picture information, and the RSVP aims at stream data continuing for some consecutive period of time and transmitted substantially at a fixed rate and is therefore hard to apply to the QoS guarantee with respect to each piece of bust data transmitted at random from the multiplicity of terminals.